Shadow rails



June 14, 1960 J. D. NESBITT SHADOW RAILS 2 Sheets-Sheet 1 Filed May 15,1953 BY JD.

1 u 15 WTE MTL m u 6 4 7 7 7 1 w s a 2 Um. 0 A h 2 United States PatentSHADOW- RAILS John D. Nesbitt, Sylvania, 0hio,.assignor, bym'esn'e assignments, to Midland-Ross Corporatioru- Cleveland,"

Ohio, a corporation of Ohio Filed May 15, 1953, Ser. No. 355,363

11 Claims: (Cl. 263-6) This invention relates toshadow-railsfor-a-fuelheated forge furnace, for use in heatingmetalbillets:uniformlymy invention, attention is directed to thefollowingpor-- tion of this specification and the drawings and claims hereof.

In. the drawings:

Fig. 1 is a longitudinal verticalsection of a furnace embodying thepresent invention.

Fig. 2 is a transverse sectional .view of the improved.

furnace.

Fig. 3 is a transverse sectional view of an alternate furnace design.

Fig. 4 is a transverse sectional view of another alternate furnacedesign.

Fig. 5 is a schematic longitudinal.representation of the- Fig. 9 is awater pipingvlayout for the work sup ort.

means of Fig. 3.

Fig. 10 shows a water piping layout for the work support means of Fig.7.

Fig. 11 shows a water piping, layout for the work support means of Fig.8.

The furnace of Fig. -1 comprises a refractory lined tunnel forming acylindrical chamber 10 which will ordinarily be supported onhorizontally disposed rails 13. atop supporting pillars 14, the tunnelhaving lateral arms 12 which rest on said rails. The tunnel is anchoredat one end to the supporting frame of which the pillars 14- form a part,the balance of the tunnel being free to move on said rails as its lengthincreasesdue to thermal expansion.

The work pieces to be heated are passed through the furnace chamber at alevel which is substantially within the central portion of the heatingchamber. The means for supporting the work at such level comprisesinternally cooled supports generally indicated at 15, the water supplypipe being indicated at 45 and thewater outlet pipe at 46. The chargingend of the furnace'is at the left as viewedin Fig. 1 and the work piecesare fed into the furnaceby a reciprocating pusher head 16 in front ofwhich the work pieces are placed by handor otherwise. Theheated'workpiecesexitfromthefurna'ce on adown wardly inclined support 17. The fluegases-exit from: thefurnacethrough front and rear: vertical flues 18 and19.

The inner lining=20 of the: tunnel 10: is' comprised: of fused bubblealumina which is a-high temperature refractory' having heat insulatingproperties.

toheat-the exposed surface of said lining toelevated temperature, thelining having ja plurality of tangential fuelinletports' 23 for thispurpose so that the-fuel will wash said surface 'and burn in contacttherewith.

Themeans for delivering the aerated fuel under pressureto the-inletports 23 comprises foreach port arefractory" nozzle-25 which projects ashort distance intosaid port. A supply pipe 27 delivers the aerated fuelunder pressure to. aholder 26 for the refractory nozzle 25.

The several fuel supply pipes27 for the several burners or fueldischarge nozzles 25 are connectedin sets-toindividual fuel supplymanifolds37, thereby permitting;

readycontrolof the heatinputto the furnace at longi tudinal intervals orzones. by control of valves 40 indi-.

vidual to supply pipes 41..whicl1.- deliver to said maniing; walls.36which. also serve to prevent .draftthrough. the lower. portion of .thefurnace and additionally serve.

to divide thelower. portionof .theheating chamber into longitudinalzones. which are useful for heat. control purposes.

In a furnace'having acircular combustion chamber. which is tangentiallyfired as. illustrated in Fig. 2 itis.

possible to maintain combustion against the refractory wall of thefurnace as a relatively thin sleeve in the chamber and maintainunusually high Wall temperatures for rapid high heat head heating. Thecentral part of the-chamber within the dashed line circle 54-is filledwith products of combustion finding their way towards the end flues.These products of combustion are relatively inactive gases as comparedto the reacting gases in the gas flame of the outer sleeve, hence thescale formation' is held to a minimum during the fast heating of thework. The temperaturesmaintained in the heating chamber, generally inexcess of 2600F., are so high as to practically preclude the use ofother than refractory or water-cooled work supports in'thefurnacechamber, and the method of firing demands that the water-cooledsupports be kept out of the sleeve or path of burning gases.

in the furnace chamber, otherwise they would chill the gases beforecombustion was complete, and would absorb heat by convection as well asradiation removing as much as 40% more heat fromthe furnace. In afurnace having of the furnace. When the furnace has an inside chamber.

diameter of about 40 inches, the burning gas sleeve has. a thickness ofabout 6 inches. 7

Where the work pieces are required to be pushed through the furnacebroadside first (as the work pieces W in Figs. 6, 7 and 8), the ends ofsaid pieces tend to become overheated. This is due to a radiationphenomenon Where the furnace wall temperature is considerably in excessof the final desired work temperature. To prevent' this. overheating thepathway 15 alongwhich the work pieces move through the furnacecomprises, irraddi tion to the internally cooledwork supportingskid'rails 47 (Figs. 6, 7 and8); a pair of internally cooled side railsEatented J une: 1.4,. l 960 A layer. ofheat insulating material-21 willordinarily. beinterposed between. said lining and the. steel casing. 22of thetunnel' 10; Fully aerated fuel, preferably gaseous, .isemployedfaster than another.

are moved. Each side rail 48 is located with respect to the moving workso as to shield it from the excessive end heating eflfect of the entireside of the furnace wall,

7 hence the end of the work piece-is said to move'in the shadow of theside rail; For this reason 'the side'rails 48 are called shadow rails.

- In rapid heating furnaces of this type billets' may be heated toforging temperature with not over 0.002 inch of scale whereasconventional forge furnaces would allow to -form at least .010 inch of.scale, usually more.

'48 which form a channel between which the work pieces a .2,94o,741" i Vthe work ends to be heatedby a hydraulic cylinder mechanism 78 fixed atthe charge end which maintains tension on the shadow rail to keep itstraight, and by a roller 76 on surface 77 which may be verticallyadjusted ;by a servo mechanism such as a hydraulic cylinder 78.

The hydraulic cylinder 78 is adapted to adjust the position of theroller 76 on the. surface 77, hence the relative vertical position ofthe shadow rail 48, by hydraulic control means 80 and temperaturecontrol means 81 respon- The improved forging die life possible with thematerially reduced scale has been remarkable, usually of the order of 2to 4 times the life formerly obtained. Where the shadow 'railsf are notused the non-uniform heating of 'the ends overheats the steel and at thesame time melts the thin scale thereon, making a sticky scale whichrapidly deteriorates the forging dies. It has been demonstrated that totake'full advantage of the rapid heating possible where a high .heathead furnace is used, if billets are especially where the furnacetemperature is over the scale melting temperature of 2440 F., if thework heats at the ends or at light sections faster than at otherportions, then the faster heating portions may easily reach 2440 F. .attheir surface and form a plastic scale before the remainder of the piecereaches forging temperature. This plastic scale' is worked into thesurface of the piece in the dies and is very detrimental to the dies,causing materially shortened die'life and subsequent machining troubles;Where shadow rails and'support rails are both used, each side pair ofshadow and support rails may be interconnected with water-cooled tubularsections 55- as shown in Fig. 7, and the flow therethrough may be'controlled by valves 56 and 57 as shown in Fig. 10. The

support rails may also be jointed by similar tubular sections 58 makingthe support rails and the shadow rails into a single structure as shownin Fig. 8. The controlled directional flow may be maintained quiteeasily by restricting fiow in alternate rails at the inlet ends thereof,and at the outlet ends of intermediate rails asillustrated by valves 56and 57 in Fig. 11.

When it is desired to heat one and only of 'bars or.

the like, a slot opening type of fast heating furnace, as

' shown in Fig. 3, may be used. Here the work W is cantilever supportedthrough "the slot opening in the side of 'the furnace by an externalconveyor 61 and external guides 62. The slot is preferably defined bywater-cooled sive to periodictemperature'readings of aradiant tern--perature responsive device 82. The periodic-adjustment of the positionof the shadow rail 48 'is preferably initiated responsive to a timeclockroperated knockout, device .83.

- A similar adjustment means may, of course, be applied to the shadowrails of Figs. 1 and 2, or of Fig. 3 when the occasion demands, but forillustration the structure portions '63. Piers 36 are notched to supporta skid, orfl guide rail 47, and a shadow rail48 is provided next adajacent the vulnerable end of the work W to prevent overheating thereof.j It is preferred to join the skid and in Figs. 7 and 9. V V W In Figs.4 and 5 a vertical bar end heating furnace is shown wherein rows of fuelnozzles 25 discharge upwards on each side of the work W being heated.The ,work issupportedrin a chain type conveyor 65 'ivhich moveswork's'upports 66 by chains 67 and 68 by sprockets at shadow'rails 47and. 48 hereby connectors 43. as illustrated centerlines 70 which aresupported 'on axles at centerline 71., Water boxes 72 form the slotopening to the heating is shown only on the vertical bar heating furnaceof Figs. 4 and 5. a a An adjustable shadow rail end heating furnace ofthe typeshown in Figs. 4 and 5 is beingused to heat leaf 7 spring blanksfor end forming where temperature distribution at the bar end determineshow the end will form,

'too cold an end giving too short a rounded stub, and tool hot causingoverheating or burning; A desired temperature balance'gives a strong,properly pointed end,'

The controlled and adjustable shadow rail is also applied advantageouslyin an operation where rod ends must be split and subsequently shaped.Extremely close temperature control of the extreme end of the rod isrequired for best die life'as well as proper formability, these beingpractically unattainable in a fast heating furnace unless properuniformity'of temperature in the piece to be hot formed is attained. 1 Ip v a While shadow rails are most. commonly employed in conjunction withskid rails as shown in Fig. 2, there'are special cases where a singleshadow rail and a'single skid rail is most advantageous, and also as inFig. 4 where the shadow rail is applied independently of skid rails. Y r

I claim: i "1. In a furnace for heating work pieces to elevatedtemperature, in combination, a heating chamber for said work pieces,means comprising internally cooled skid.

rails for conveying said work pieces broadside first through saidchamber, and internally cooled side rails between which said work piecesmove-through said chamber, the side rails being adapted to preventoverheating the ends of said pieces by radiation cooling thereof.

2. The combination according'to claim 1, wherein adjacent skid and siderails'are interconnected at longitudinal intervals by tubular members sothat cooling 'fluid flowing through said skid rails will also flowthrough said tubular members. V

3. The combination according to claim 1, wherein adjacent skid and siderails are interconnected at longitudinal intervals by tubular members sothat cooling fluid flowing through the skid rails will also flow throughsaid tubular members, and adjacent skid rails are interconnected by asecond series of tubular members in a manner allowing transfer ofcooling fluid through tubular'members of the second series from one skidrail to the other.

4. The combination according to claim 1, wherein the furnace heatingchamber is cylindrical and is tangentially fired whereby to constituteits Walls sources of radiant heat, and comprising wall'means extendingac'ross the lower half of the heating chamber at longitudinal intervalschamber, and the work passes through the slot opening from the charge tothe discharge ends 73 and 74 of the conveyor; 7,

A water-cooled shadow rail 48 is supported next above and being adaptedto support saidfrails spaced'from the chamber walls whereby to provideunrestricted'circumferential passage for burning gases. adjacent thewalls. I '5. In the art of heating elongate work pieces an end of whichnormally tends to overheat, in combination, wall means forming a heatingchamber, means for conveying said work pieces along a path of travel'Withsaid end exposed in said chamber, an internally cooled shadowrailsupported in said chamber along said path next adjacent said end, andmeans for adjusting the position of the shadow rail towards or from saidend responsive to the temperature attained thereby in the chamber.

6. The combination according to claim 5 which comprises internallycooled skid rails for supporting the work in the chamber.

7. An end heating furnace comprising, in combination, Wall means forminga heating chamber and defining a slot where through work ends to beheated extend as they are moved through the furnace; conveyor means foradvancing work pieces whose ends are to be heated through the slot andheating chamber; an internally cooled shadow rail supportedlongitudinally in the furnace axially adjacent the ends of the workpieces as they move through the furnace; and means for adjusting theshadow rail to work end distance.

8. An end heating furnace according to claim 7 wherein the means foradjusting comprises temperature responsive means responsive to work endtemperatures, a servo mechanism for moving the shadow rail to or fromthe Work ends, and control means responsive to the temperatureresponsive means and adapted to actuate the servo mechanism.

9. In a furnace for heating to elevated temperature work pieces aportion of which normally tends to overheat in said furnace, incombination, a heating chamber for said work pieces, means comprising atleast one internally cooled skid rail for conveying said work piecesthrough the chamber, means comprising at least one internally cooledshadow rail aligned with said skid rail to prevent overheating of saidportion of the work pieces as they are conveyed through the heatingchamber, and tubular members interconnected at longitudinal intervals tosaid skid and shadow rails so that cooling fluid flowing through theskid rail and shadow rail may also flow through the tubular member.

10. In the art of heating work pieces for hot working,

in combination, a plurality of work pieces having a part to be heatedincluding a portion which normally tends to overheat in a fast heatingfurnace, wall means forming a heating chamber for a fast heatingfurnace, conveyor means for moving said work pieces along a path withsaid parts to be heated in the heating chamber and the portions normallytending to overheat defining a line of travel therein, an internallycooled shadow rail in the chamber and extending next adjacent the lineof travel whereby to prevent overheating of said portions normallytending to overheat by radiation cooling thereof, and means responsiveto temperatures attained by the portion normally tending to overheat formoving said shadow rail to or from said portion in a manner tending tomaintain the attained temperature thereof substantially constant.

11; In the art of heating work in a heating chamber, in combination,means for conveying said work along a path of travel through the chamberfrom an inlet thereto to an outlet therefrom, an internally cooledshadow trail disposed in the chamber and extending along the path oftravel, and means for adjusting the position of the shadow rail to orfrom said path of travel, said adjusting means comprising a tensionmaintaining device for keeping the shadow rail straight, and a wheel atone end of the furnace adapted to roll toward or from the path oftravel, said wheel supporting an end of the shadow rail.

References Cited in the file of this patent UNITED STATES PATENTS715,029 Dailey Dec. 2, 1902 751,720 Dailey Feb. 9, 1904 2,457,846Strickland Ian. 4, 1949 2,652,240 Nesbitt Nov. 20, 1950 2,637,544 ZotosMay 5, 1953

